


A Certain Slant of Light

by sleepypercy



Category: Supernatural
Genre: Dark fic, Frottage, M/M, Mark of Cain, Mark of Cain!Dean, Sex, Violent Thoughts, unaware sam
Language: English
Status: Completed
Published: 2015-02-22
Updated: 2015-02-22
Packaged: 2018-03-14 13:29:42
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 1,368
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/3412385
Author URL: https://archiveofourown.org/users/sleepypercy/pseuds/sleepypercy
Summary: <blockquote class="userstuff">
              <p>
  <i>The softness in Sam’s voice goes straight to Dean’s chest, tugs on that heartstring that’s now cross-wired to bloodlust.</i>
</p><p>After fighting Cain, Dean's feeling the effects of the Mark of Cain stronger than ever. He wakes up his brother, who mistakes the look in his brother's eyes for something else.</p>
            </blockquote>





	A Certain Slant of Light

**Author's Note:**

> This idea wouldn't leave me alone for a few days. Thanks to [](http://ephermeralk.livejournal.com/profile)[ephermeralk](http://ephermeralk.livejournal.com/) for being unbelieavably awesome as usual and doing a last-minute beta for me even though it was way past her bedtime. Title from Dickenson poem. I hope she's not appalled.

Electric heat vibrates through the tips of Dean’s fingers as he watches his brother sleep. Chest moving up and down in quiet inhales and exhales. Hair splayed feather-soft on his pillow. Sleep turns even the most hardened hunter into something more innocent, and Dean’s reminded of when they were both tiny, Sammy still in a crib. After the fire, the anxiety of losing Sam had been strong, making Dean pad out of bed two, three, ten times a night just to check on his little brother. He’d peer through the crib bars, reaching out to touch Sam’s baby-soft skin, stroking a cheek or wrist just to reassure himself that his little brother was still alive and warm and breathing.

It wasn’t until Sam outgrew his crib and John - picking up on Dean’s anxiety - decided to have the boys share a bed that Dean finally slept through the night.

Right now, he can feel the tug of that fraternal bond between them, steadfast as ever. It’s that very thing that makes him want to see Sam bleed. The Mark pulses on his forearm, hungry for death and blood. But, more than anything, hungry for Sam’s blood. His brother. His family. The one murder he’d never get over, never recover from. Never stop craving.

Knowing how much he’d regret it doesn’t stop Dean from giving in to the thought of how good it would feel to slash across that golden skin. Blade pressed to his stomach, running a crescent-shaped line right below his belly button. It would be such a release, snapping the tension in Dean’s muscles like a rubber band, watching the blood dripping down, seeing Sammy’s surprised face as his hands rush to hold his intestines inside.

He’s not entirely aware of crossing the room, placing his hand on the strip of skin revealed by Sam’s shirt riding up. But as soon as his fingers touch Sam’s belly, his brother stirs, hunter’s instincts making him dart a hand out to grab Dean’s wrist even while he blinks himself awake.

“Whasha doin’?” Sam sleep-drunk slurs. He squints down the bed at his brother, eyes softening just a little at the way the fingers on Dean’s other hand trail across the imaginary line where Sam’s wet insides would spill out.

“Sorry,” Dean says, and it’s strange how sincere he sounds. “Didn’t mean to wake you. Go back to sleep, Sammy.”

But Sam shakes his head, even as his eyes flutter back a little, mind still caught in that space between sleep and awake. Damn, the kid’s dead tired. Dean wonders how many late nights Sam has spent tossing and turning. Wonders if Sam’s still got nightmares filled with sanguine lights flashing in the hallway, Dean stalking Sam like wide-eyed prey, ready to swing a hammer right through the bones of his skull.

“No.” Sam smacks his mouth a little, tongue coming out to wet his dry lips. “I… s’okay, Dean. You c’n stay.”

He tugs at Dean’s arm, gently insistent until Dean kneels on the bed, one hand on Sam’s thigh to steady himself as Sam pulls himself up to a sitting position. Dean can see pillow creases on one side of Sam’s flushed cheeks, winding red roadmaps that Dean would love to trace with a knife.

“So proud of you,” Sam says in a mumble. His thumb rubs small circles into Dean’s wrist, eyes closing just a little, head bowing forward. “Know you can fight this. I know it, Dean.”

Bleary hazel eyes peer at Dean through a fringed mess of bedhead. Sam lets go of Dean’s wrist to slide his hand along the edge of Dean’s jaw, cupping it behind his neck and pulling his brother forward. Bold enough to do this without the clarity of full consciousness.

Sam’s mouth is sleep-soft and sloppy. Tongue moving thick as he presses against Dean’s lips while his fingers curl into Dean’s short hair. Dean lets himself fall into the familiar sensation of his brother’s mouth, fingers grabbing at Sam’s cotton t-shirt, pulling them as close as possible.

“Did - didja miss me?” Sam asks wistfully against Dean’s mouth. The softness in Sam’s voice goes straight to Dean’s chest, tugs on that heartstring that’s now cross-wired to bloodlust.

Fuck, all he can think about is how beautiful Sam would look painted in blood red. How those puppy-dog eyes would turn wide and shocked if Dean tore a knife-shaped hole right into his heart. He moves himself until he’d straddling Sam’s hips, and underneath him is Sam’s cock pressing hot and half-hard against his ass. He can feel the guilt like a far-away thought tucked deep into his brain. He knows it’s there, but the Mark keeps pulsing out bloody thoughts around every emotion; the more he loves Sam, the more he wants to hurt him.

“Yeah,” Dean says huskily while moving himself back and forth, pleased with the way Sam leans back down, eyes fluttering back and mouth turning slack as soft whines start pouring up his throat. “It’s been a while.”

Sam’s hands grab onto Dean’s thighs when he starts rocking harder, encouraging Dean to move faster. Part of Dean wants to feel his brother inside, stretching Dean, filling that space inside Dean that he’s pretty sure was always meant for his brother. But this is also good. Feeling the way Sam’s cock stretches the crotch of his pajamas, rubbing wetly through the cotton layer of Dean’s boxers, riding the groove of Dean’s ass.

Dean covers one of Sam’s hands with his own, back arched as he works his hips in pendulum swings and tight circles. His other hand reaches back to cup the back of Sam’s cock through the flannel pajama bottoms, pressing the hot shaft harder against his ass.

Looking down, Dean sees Sam’s head thrown back as he writhes on the bed, working his hips in time with Dean’s. It would be so easy to slice that pretty, exposed neck. Make a beautiful wet red arc from the severed carotid artery. Dean licks his lips at the thought of Sam’s cheeks dotted with blood, and he can’t help the memory floating to the surface, eight-ball fortune pushing up from the black. A smaller, baby-faced Sam asleep in his bed, Dean bent over, magic marker in hand as he fills his baby brother’s cheeks and nose with replicas of Dean’s own freckles. Thirteen-year-old Dean still irritated at Sam’s week-long teasing after catching Dean trying to bleach off his spots with pickle juice.

He just manages to curb that bloody impulse, restrains himself from reaching down to grab at the knife he knows his little brother’s got tucked under his pillow. A precaution Sam’s taken up ever since they’d been shot and killed in their own beds.

The feel of Sam’s hand sliding inside Dean’s boxers catches him by surprise, and Dean gasps at the fingers closing around his dick. The pleased smile on Sam’s face reminds him of how young Sammy had been strangely proud of the spots on his face. Hadn’t been as upset as Dean had expected, wearing his counterfeit freckles proudly until they’d finally faded from his skin.

When Sam’s eyelids fall to half-mast and his mouth gapes open, little hiccuping breaths coming up his throat, Dean knows his brother is close. Pressing himself down against Sam’s chest, Dean scoots down to line their dicks and bellies up against each other, bodies rubbing until they both finally come, hot and wet inside their pajamas and panting into each other’s mouths.

Dean thinks about staying. Falling asleep curled up against his brother’s warm body, Sam’s arm flung around his shoulder. But he really doesn’t trust himself. With the residual endorphins running through his system, strengthening that connection between him and his brother, Dean can feel the Mark of Cain whispering urges that physically hurt him to deny. He wants to wraps his fingers around Sam’s throat, press hard and tight and feel the life drain from his body.

With effort, he makes himself stand up, walk away. A flash of disappointment passes behind Sam’s eyes, but Dean knows it’s for the best. As long as Sam’s still breathing when Dean walks away, he’ll call tonight a win.


End file.
